Most half breeds live as refugees. Some time after the establishment of New Helghan the Helghast forcibly removed as many Half breeds, and humans, from New Helghan as possible and forced them into Vekta City. Little respect is paid to the Half Breeds in Vektan territory where they experience social segregation and violence in Vekta, and are viewed as traitors by pure strain Helghast and are treated far more harshly as such. Despite supposedly being welcomed back to New Helghan as citizens they are considered undesirables. While half breeds have been seen through out the series Killzone: Shadow Fall is the first game to show the way society treats them.
They retain traits of both humans and Helghast, such as pale skin and in most cases hair. They often do not need respiration devices, but Hakha has pipes going to the back of his skull. This was likely a military cybernetic enhancement. In general, half breeds are physically stronger, tougher and heal faster than an average human (though not as much as a pure helghast), as well as have calmer, more patient and less hostile mentalities than the average helghast, giving them more of each races genetic strengths rather than weaknesses.